Mechanisms of TGF beta inhibition of LUNG endodermal morphogenesis: The role of T beta RII, Smads, Nkx2.1 and Pten

作者：Xing Yiming; Li Changgong; Hu Lingyan; Tiozzo Caterina; Li Min; Chai Yang; Bellusci Saverio; Anderson Stewart; Minoo Parviz^*

来源：Developmental Biology, 2008, 320(2): 340-350.

DOI：10.1016/j.ydbio.2008.04.044

• lung morphogenesis
• branching morphogenesis
• TGF beta
• T beta RII
• Smads
• NKX2.1
• SpC
• Pten
• endoderm

Transforming growth factor-beta is a multifunctional growth factor with roles in normal development and disease pathogenesis. One such role is in inhibition of lung branching morphogenesis, although the precise mechanism remains unknown. In an explant model, all three TGF beta isoforms inhibited FGF10-induced morphogenesis of mesenchyme-free embryonic lung endoderm. Inhibition of budding by TGFJ was partially abrogated in endodermal explants from Smad3(-/-) or conditional endodermal-specific Smad4(Delta/Delta) embryonic lungs. Endodermal explants from conditional TGF beta receptor II knockout lungs were entirely refractive to TGF beta-induced inhibition. Inhibition of morphogenesis was associated with dedifferentiation of endodermal cells as documented by a decrease in key transcriptional factor, NKX2.1 protein, and its downstream target, surfactant protein C (SpC). TGF beta reduced the proliferation of wild-type endodermal cells within the explants as assessed by BrdU labeling. Gene expression analysis showed increased levels of mRNA for Pten, a key regulator of cell proliferation. Conditional, endodermal-specific deletion of Pten overcame TGF Vs inhibitory effect on cell proliferation, but did not restore morphogenesis. Thus, the mechanisms by which TGF beta inhibits FCF10-induced lung endodermal morphogenesis may entail both inhibition of cell proliferation, through increased Pten, as well as inhibition of interference with morphogenetic mediators such as Nkx2.1. Both of the latter are dependent on signaling through T beta RII.

• 出版日期2008-8-15